Circuit controller



Feb. 13, 1940. c c, BRADBURY 2,190,468

CIRCUIT CONTROLLER Filed May 6, 1931 4 SheetsSheet 1 58 2 7L @L Z5.

Feb. 13, 1940. c. c. BRADBURY CIRCUIT CONTROLLER Filed May a, 19:1

4 Sheets-Sheet 2 KW R @W %W Q Q 9 0% Mania? CZWOTJCflJZZQZZUy 1940- c.c. BRADBURY 90,

CIRCUIT CONTROLLER Filed May 6, 1931 4 Sheets-Sheet 3 9% B 67Cfnradbzuzg 24, m jm zw Q Feb. 13, 1940. c c BRADBURY 2,190,468

CIRCUIT CONTROLLER Filed May 6, 1937 4 Sheets-Sheet 4 Patented Feb. 13,1940 UNITED- STATES PATENT OFFICE CIRCUIT CONTROLLER Application May 8,1537, Serial No. 141,081

9 Claims.

direction in periodic steps through a pawl and.

5 ratchet mechanism actuated by a constant speed -motor.

In a circuit controller of the above type, such for instance as thatforming the subject matter of the copending application of Rex E.Bassett,

l0 Jr., Serial No. 240,163, filed November 12, 1938 (Case 10), aconstant speed motor is utilized to drive a single step cam at constantspeed. The cam in turn imparts oscillatory motion to a pivotally mountedpawl carrying arm that is forced to follow the cam by a relatively heavyspring. A pawl provided with a toothed portion adapted to engage aratchet wheel is pivotally mounted upon the arm and adapted to impartmovement to the ratchet wheel as it is reciprocated by the oscillationof the arm. The pawl is held in engagement with the ratchet wheel by thespring, mentioned above, which is preferably secured to the pawl and toa pivotally mounted dog adapted to prevent retrograde motion of 2 thewheel. The ratchet wheel is secured to and drives a shaft upon which ismounted a series oi. cams adapted to actuate resilient contact carryingmembers biased to circuit closing position.

A controller of the above type permits the use :10 of relativelyinexpensive resilient contact carrying members for the reason that thedisengagement of the contacts is made to depend not upon the resiliencyof the contact carrying members themselves, but upon the rapidity ofmovement of the cams.

The rapidity of movement .of the cams is dependent upon the strength ofthe spring biasing the pivotally mounted pawl carrying arm toward themotor driven cam. It is, therefore, desirable to make the spring strongin order to eii'ect rapid disengagement of the contacts. However, it hasbeen found thatif the spring is made too strong the ratchet wheel isgiven a sudden impulse which carries it more than the unit distance itis designed to be moved by the cam actuated pawl and ratchet mechanism.In other words, if the spring is too strong it causes overrunning.

Circuit controllers of the type forming the subject matter of the abovementioned Bassett application, were designed particularly for use withwashing machines. While these machines normally can be operatedaccording to a predetermined cycle of operations for which thecontroller is designed, it sometimes happens that it is desirable eitherto hasten or omit the performance of certain functions. For this reasonthe controllers are provided with means permitting manual operation ofthe cams, whereby certain operations may be hastened or'omittedentirely.

The primary object of the present invention is to provide a new andimproved controller. of the type described above in which thepossibility of overrunning is eliminated.

A further object of the present invention is to It provide a controllerof the above type with means adapted positively to prevent overrunningof the ratchet wheel and controller when the latter is actuated throughthe pawl and ratchet mechanism, thereby permitting the use of springs'23. sufliciently strong to enable the controller to be moved withdesired rapidity.

A further object of the present invention is to provide a controllerwith means adapted positively to prevent overrunning of the controller,but so designed that the controller may be manually rotated whereby theperformance of func tions by the machine controlled thereby may beselected, hastened or omitted, as desired.

Further objects and advantages of the inven- 1 tion will become apparentfrom the ensuing description in which reference is had to theaccompanying drawings illustrating embodiments thereof.

In the drawings: V

Fig. 1 is a fragmentary vertical section of a cabinet showing one formof a circuit controller, constructed in accordance with the presentinverstion, mounted therein;

Fig. 2 is a side elevation of the circuit con: troller of Fig. 1, withthe housing and parts there of shown in section;

Fig. 3 is a fragmentary longitudinal section taken through the pawl andratchet mechanism and the circuit controlling portion of the controller;

Fig. 4 is a perspective view showing the details of a prong contact andmovable contact carrying member of the circuit controller;

Fig. 5 is a front elevation, partially in sec tion, of the multiplesection switch actuating cam;

Fig. 6 is a rear elevation, partially in section, of the switch members;

Fig. '7 is a transverse vertical section taken along the line |--l ofFig. 2, and showing the pawl and ratchet mechanism and the means forpreventing overrunning of the controller;

Fig. 8 is a fragmentary top plan view of the details shown in Fig. 7;

Fig. 9 is a view similar to that shown in Fig. 7

v of a modified form of means for preventing overrunning; and

Fig. 10 is a-vlew similar to Fig. 8 of the modification shown in Fig. 9.

The circuit controller embodying the present invention and illustratedin Figs. 1 to 8, inclusive, comprises a fixed multiple socke receptaclesecured in suitable fashion to the washing machine, or the like, and aunitary removable casing'provided with prong contacts adapted to beinserted into the sockets. The sockets are connected in circuit with asource of energy and to the various devices that are to be controlled bythe circuit controllers;

The unitary removable casing carries not only the circuit controller andthe actuating means I therefor, but also a manually operable knob whichindicates the position of the controller and by means of which theoperation of the apparatus may be hastened or selected, as hereinafterdescribed. 7

Referring first to Fig. 1, the controller, indicated generally byreference numeral I is shown installed in position on a side wall l2 ofa washing machine cabinet. In this position the unitary removable casingl3 of the controller is shown adjacent the fixed receptacle l4 where itis supported not only by the prong contacts (see Fig. 2), but by ahorizontally disposed bracket |5 to which it is secured by a surroundingsteel strap IS. The controller is provided with an indicating andadjusting knob |1 cooperatively associated with a dial plate (not shown)comprising suitable indicia for indicating the various functions thatare performed by the washing machine.

From Fig. 2 it may be noted that the casing I! is formed substantiallyin the shape of an elongated cup, the front end of which is closed by asubstantially circular combined closure and support 2| made of suitableinsulating material. The closed rear end 22 of the casing I3 is providedwith a flanged opening 23 through which extends a pair of conductors 24leading to a constant speed motor, indicated generally by referencenumeral 25, mounted within the casing.

The motor 25 is supported in the rear end of the casing by the endportion 22 of the latter and a metallic support 26 secured within thecasing approximately halfway between the end 22 and the insulating frontsupport 2| by the screw bolts 21 and spacing blocks 21A. Theintermediate support 26 is separated from the casing by a relativelythin insulating sheet 28.

The motor may be of any well known type of construction and comprises a.laminated field core 29, a p rtion of which supports a field coil 30.The field core is supported upon a pair of external bosses 3| only oneof which is shown, formed integrally with a gear casing 32 supported inturn upon the intermediate support 26 by a plurality of screw bolts 33.The casing 32 is spaced from the intermediate support by a plurality ofspacing blocks 34 surrounding the bolts. The field core 29 is secured tothe vertical bosses 3| by double-ended nuts 35, the other ends of whichreceive screw bolts 36 passing through suitable apertures in the rearportion 22 of the casing I3.

' The motor .25 is preferably of the shaded pole self-starting typeprovided with shading coils 31 encircling portions of the laminatedfield core 29- between which is mounted an armature (not shown) of usualtype. The armature is mechanically connected through gears in casing 32to a shaft 38 (see Fig. 3) extending through an external boss 39 formedat the front side of the gear casing and to the end of which is mounteda single step cam 4|.

The cam 4| is rotated at a reduced speed by the motor and is adapted todrive through a pawl and ratchet mechanism, to be described fullyhereinafter, a cam shaft 45 Journaled for rotation in a brass bearingbushing 46 mounted centrally of the intermediate support 26 and acombined spacer ,and bearing bushing 41, a reduced portion 48 of whichis mounted in the front insulating support 2|.

The method of mounting the cam shaft, as well as the cam and switchstructure about to be described, form no part of the present invention,but are disclosed and claimed in the previously mentioned copendingapplication of Rex Earl Bassett, Jr.

A multiple section cam 5| comprising a guiding portion 52 and four camsurfaces or sections 5|A to 5|D, inclusive, the diameters of whichincrease with the distance of the particular cam section from thesupport 2|, is mounted for rotation with the cam shaft 45. The cam isfixedly secured to a hub 53 by means of an annular shoulder 54 providedat the front end of the hub, seating in a recess 55 formed in the frontend of the cam, and a rolled-over portion 56 securing in place anannular washer 51, also mounted in a recess formed on the rear side ofthe cam 5|. The hub is secured to the cam shaft 45 near the intermediatesupport 26 by suitable means, such as the knurling 58. The cam isseparated from the front combined spacer and bearing bushing 41 by anintermediate insulating spacer 59.

The cam sections 5|A to 5|D have associated therewith resilientgenerally longitudinally extending contact carrying switch blades 6|A toMD, inclusive. These blades are provided with cam engaging rear portions62 and transversely extending perforated portions 63 through which prongcontacts 64 extend. The prong contacts are provided with shoulders 65adapted to abut against the front side of the support 2| and are peenedover as indicated at 66, whereby the contact forms the sole support forthe contact carrying blade. The blade is provided with a. longitudinalfiange 61 adapted to enter a recess in the support whereby the blade issecured against movement on the support.

The various prong contacts associated with the switch blades BIA to 6|D,inclusive, have been indicated by the reference numerals 64A to 64D,inclusive, and the construction of the combined prong contact and switchblade may be noted best from Figs. 3 and 4.

The resilient switch blades carry contacts 68A to 68D, inclusive. Thelatter are adapted to be selectively moved into and out of engagementwith fixed contacts 69A to 69D, inclusive, located radially inward fromthe first mentioned contacts and mounted upon a substantially rigidsupport H. The support H, as may be seen from Fig. 6, substantiallysurrounds the cam shaft 45 and it is secured to the front suport 2| bymeans of a prong contact 12 and a rivet 13.

The prong contacts 64A to 64D, inclusive, and I2 are adapted to beinserted into similarly located sockets 14A to 14D, inclusive, and 15mounted in a support 16 forming a closure 'for the rear end of the fixedreceptacle l4 to which it is secured by a bent-over tongue portion 11.The support 16 is made of three strips 8|, 62

and 88 of insulating material provided with apertures coaxially locatedwith respect to the various contact prongs. The sockets 14A to "D,inclusive, and I5 are formed with flanged portions 84 adapted to seat inrecesses 85 formed in the middle strip 82 and are provided withtongue-like terminals 88 adapted to extend through recesses 81 formed inthe front strip 82 whereby, when the strips are assembled in theposition shown, particularly in Fig. 3, the sockets are securely held inplace.

The contact terminals 88 may be connected to a suitable source of energyand the various control devices associated with the apparatus to becontrolled. If the controller is to be used with a washing machine, theconnections may be made after the disclosure in the copendingapplications oi Rex Earl Bassett, Jr., filed February 14, 1935, SerialNo. 6,425, Aaron A. Loweke, filed May 8, 1936, Serial No. 78,692, or RexEarl Bassett, Jr., and John W. Chamberlin, Serial No. 129,429, filedMarch 6, 1937, the last mentioned of which contains a completediscussion of a washing cycle of the type for which the presentcontroller is specifically designed. According to these disclosures thefixed contacts 89A to 89D, inclusive, are connected to one terminal ofthe source of energy. The movable contacts associated therewith areconnected through prong contacts and sockets, with one terminal of thevarious control devices, the other terminals of which are connected tothe other terminal of the source of energy. Thus each time the contacts68 and 69 are in engagement, the control device is energized. Inpractice the cam 5IA controls the motor 25, and from Fig. 6 it may beseen that the contacts 88A and 89.41 are closed except for a briefinterval, which corresponds to the off position of the apparatus andfrom which it is necessary manually to move the controller through theindicating knob II. Once moved from the "oif position, the motor 25 isenergized and rotates the cams through one complete revolution,corresponding to the cycle of operation of the machine.

The indicating knob I1 is secured to the front reduced end 88 of camshaft which extends outside the receptacle I4 and cabinet wall I2. Itmay be secured to the shaft by suitable means, such as the set screw 89.

A spacing and insulating bushing 9I surrounds that portion of cam shaft45 within thefixed receptacle I4. The bushing 9| is secured againstlongitudinal of displacement along the shaft by a collar 92 seated in agroove 93 thereof. The various electrical conductors (not shown) lead tothe terminals 86 through a flanged opening 94 provided on the lower sideof the fixed receptacle I4, as shown in Fig. 2.

In the description of the means for imparting periodical rotary motionto the cam shaft and the means for preventing over-running thereofreference will be had in particular to Figs. 2, 3, 7 and 8.

The movement imparting means comprises a pawl and ratchet mechanismadapted to be actuated by means of the cam 4| which is, as heretoforedescribed, driven at a constant speed by the electric motor 25. The camis adapted to impart oscillating motion to a pawl carrying arm 91pivotally mounted upon a stud 88 secured in suitable manner to theintermediate support 28.

From Figs. 2, 7 and 8 it may be noted that the pawl carrying arm 81 ison the opposite side of support 28 from the cam 4|, but is provided witha transverse projection 88 located substantially halfway between theopposite ends thereof and extending into the path of movement of the cam4| through an aperture III provided in the intermediate support. Thetendency of the pawl carrying arm to bind is avoided by providing thearm with a second projection I82 extending toward the cam and adapted toride on the guiding portion 52 thereof.

A pawl I88 is pivotally mounted upon a pin I84 fixedly secured to thefree end of the arm 81 and is guided in its movement by a pair ofwashers I85 mounted on opposite sides thereof on the pin I84. The pawlI88 is approximately one-half the length 01' the pawl carrying arm 91and extends tangentially toward a ratchet wheel I88 fixedly mounted oncam shaft 48 and is provided with a tooth engaging portion I81 adaptedto engage the teeth of the ratchet wheel.

The tooth engaging portion I8! is tapered in form and is provided with aflat upper portion I88 disposed at an angle of approximately 45 adaptedto engage a similarly disposed extension I89 of a stop arm II8 pivotallymounted upon a pin III fixedly secured to the intermediate support 28. Adog II 2 is also pivotally mounted upon the pin III and is spaced fromthe stop arm by a washer H3 and from the intermediate support by asecond washer II4.

Referring now particularly to Figs. 7 and 8, it may be noted that thestop arm H8 is provided with an upper broadened and curved surface I I5displaced forward from the plane of the pawl and ratchet wheel. Themovement of the stop arm toward the ratchet wheel and the surface I88 ofthe pawl is prevented by a pin II8 mounted upon the intermediate support26 between the arm and the ratchet wheel and adapted to abut against theconcave lower surface III of the arm.

The stop arm as well as the pawl I83 and dog II2 are maintained inresilient engagement with the teeth of the ratchet wheel by means of ahelical tension spring II8 secured at its ends to pins I2I andI22mounted upon the pawl and dog, respectively. These pins are locatedat a distance farther from the axis of rotation of the ratchet wheelthan a line passing through the centers of the pivot points I84 and IIIof the pawl and dog, respectively. The underside of spring II8 engagesthe top curved surface II5 of the dog, and is thus given a generallyV-shaped form because the highest point of the curved surface H5 isbeyond a line passing through the pins HI and I22. The pivot points 98,I84 and III of the pawl carrying arm 91, the pawl I83 and dog II2 aresubstantially equidistant from each other and from the axis of rotationof the ratchet wheel. These pivot points are also at a radial distancefrom the axis of rotation greater than the radius of the wheel, wherebya single spring such as that illustrated is enabled not only to maintainthe pawl and dog in engagement with the ratchet wheel, but also tomaintain the pawl carrying arm 91 in cooperative relationship with theconstant speed cam 4|. Furthermore, the arrangement is such as willpermitof the manual rotation of the cam shaft by the indicating knobwhenever it is desired either to hasten or select performance of certainfunctions by the apparatus controlled by the circuit controller.

When it is desired to place the apparatus in operation, the indicatingknob I1 is manually turned in a clockwise direction from its offposition, in which all the circuits controlledby the controller areopen, to energize the motor 20. The control is such, as explained above,that once the motor is energized, it remains energized until thecontroller has completed a single revolution and thereby caused theapparatus to go through a cycle of operations, which in the case of awashing machine includes the steps of washing, rinsing and extracting.

Once the control motor is energized, it drives the cam 4| at a constantspeed through the gears housed in casing 32. As the cam rotates, itactuates the pawl carrying arm 91 in a counterclockwise direction, asviewed in Fig. 7, against the bias of the spring H8. The pawl carryingarm is gradually moved to an extreme counterclockwise position and thenfalls ofi the high point of the'cam 4I. The spring IIB immediately andforcibly actuates the arm 91 in a clockwise direction and moves theratchet wheel a unit distance. It the stop arm IIO were not provided andthe spring II8 made heavy enough to provide the desired rapid movementof the cam shaft, the arm 91 might be moved so rapidly that the pawl I03would give the ratchet wheel a sudden impulse, such that would cause theratchet wheel and cam shaft to rotate more than a unit distance. Thisoverrunning is possible because, when the pawl tooth I01 strikes aparticular tooth, it strikes it with considerable force, and if theforce were great enough the impulse transmitted to the wheel would causethe ratchet wheel to raisethe pawl just as though the cam shaft wererotated manually.

This overrunning of the clutch is, however, prevented by the stop arm H0which wedges the pawl tooth I01 therebetween and the ratchet wheel. Whenthe pawl reaches its limiting position, as indicated in Fig. '7, thesuriace I00 of the pawl abuts against the flanged portion I09 of thestop arm, thereby wedging the pawl tooth I01 between a ratchet tooth andthe stop arm. Thus, even though a relatively heavy impulse istransmitted to the ratchet wheel, the spring II8 acting through the stoparm prevents upward movement of the pawl by the ratchet wheel;consequently overrunning of the clutch is prevented.

During the normal course of operation of the controller by the motor 25,the cam shaft is actuated in a single direction in periodic steps ofunit distance. In some instances it is desirable either to hasten oromit certainfunctions of the apparatus controlled by the controller andfor this reason it is desirable that the controller be so constructedthat it can be manually operated. The present controller is constructedin this fashion and whenever it is desired manually to rotate thecontroller the indicating and adjusting knob I1 is turned in a clockwisedirection. The dog II2 permits the ratchet wheel to be rotated in thisdirection, but not in the opposite direction. When the indicating knobis rotated in aclockwise direction, the pawl tooth is forced upwardly bythe ratchet wheel, a tooth of the latter engaging the bottom of the pawltooth and forcing the latter upward against the bias of the spring H8.The spring IIB should-therefore, be made heavy enough to obtain thedesired rapidity of movement of the cam shalt, but not too strong toprevent manual rotation of the controller.

The modified form of construction illustra in Figs. 9 and 10 issubstantially the same as that just described, with the exception thatthe forms of the dog and stop arm have been changed slightly. For thisreason'it is not believed necessary to give a detailed description ofthe construction oi the entire controller, and thus only the escapementmechanism has been illustrated and is described in detail below.

From Figs. 9 and 10 it may be seen that-the cam 4| is adapted to impartoscillatory movement to the pawl carrying arm 91 through the projection99 formed integrally with the latter and extending through an apertureI0l on the intermediate support 29 into cooperative relationship withthe cam. The pawl carrying arm 91 is pivotally mounted on theintermediate support upon the pin 98 and hasa pawl I03 pivoted theretoat its free end upon a pin I04. The pawl I03 is mounted between a pairof washers I05 also mounted upon the pin I04.

A ratchet wheel I 06 is adapted to be engaged by the tooth I01 of thepawl so that as the pawl carrying arm is oscillated the pawl is given areciprocatory motion and rotates the ratchet wheel I06 a unit distanceupon each oscillation of the arm.

The pawl I03 is provided with a diagonal upper surface I08 adapted toabut against a pin I3I carried by a stop arm I32 pivotally mounted uponthe pin I I I secured to the support 26. The movement of the stop armI32 toward the ratchet wheel is limited by a pin IIB secured to thesupport.between the lower concave surface I33 01 the stop arm and theratchet wheel. Retrograde motion of the ratchet wheel is prevented bythe 1 dog I34 also pivotally mounted upon the pin III. The pawl I03, thedog I34 and the stop arm I32 are all biased toward the ratchet, wheel'by .a helical tension spring I I8 mounted upon pins I2I and I22 securedto the pawl and dog, respectively.

The stop arm is provided with a sector shaped forwardly extendingprojection I35 against the upper side of which the underside of thehelical springs abuts, thereby forcing the stop arm downward intoengagement with the pin H6.

It may be seen from Figs. 9 and 10 that the construction of theescapement mechanism is substantially the same as that described above,and that the pawl carrying arm 91, the pawl I03 and the dog I34 arepivotally mounted at points corresponding to those at which the similarelements of the previous modification were mounted. The spring H8 islikewise mounted in like manner to the pins I2I and I22, which arelocated, with respect to the pawl and dog, in such manner that thelatter are biased into engagement with the ratchet wheel.

The operation of the modification just described is substantially thesame in all respects as the operation of the modification lastdescribed. The cam 4| is rotated at a constant speed by the controlmotor and imparts oscillatory movement to the pawl carrying arm 91. Thelatter in turn imparts reciprocating motion to the pawl I 03 of anamplitude such as to impart rotation to the ratchet wheel I09 in steps 0a unit distance upon each oscillation.

en the projection 99 or the pawl carrying arm 91 falls of! the highpoint of cam 4|, the spring I I8 suddenly eflects movement of the pawlcarrying arm and pawl in a clockwise direction, as viewed in Fig. 9,thereby imparting a sudden impulse to the ratchet wheel. When the pawlreaches the limit of its movement in a clockwise direction. the diagonalsurface I08 thereof en- ,lflfles the pin l3! of the stop arm and thelatter securely wedges the pawl tooth I01 therebetween and a tooth onthe ratchet wheel. Thus overrunning of the cam shaft is prevented.

The cam shaft may be rotated manually in the same manner as the camshaft of the previously described modification for the reason that asthe cam shaft is rotated the teeth on the ratchet wheel force the pawlI03 upward and the latter, acting through the pin HI and spring engagingprojection I35, lifts the central portion of the spring a sufllcientdistance so that the pawl tooth I01 rises an amount sufficient to enablethe wheel to beturned.

The above specifically described embodiments of the present inventionare intended to be illustrative only and not to limit the invention inany manner.

' I claim:

1. In a drive mechanism for a controller or the like, the combinationincluding a ratchet wheel, a pivotally mounted pawl mounted upon anoscillatable arm,-means for oscillating said arm through a predeterminedangle whereby predetermined reciprocatory movement is imparted to saidpawl, a pivotally mounted dog for preventing reverse movement of saidratchet wheel, a spring connecting the pawl and dog, said spring beingmounted on said pawl and dog at points spaced farther from the axis ofrotation than a line passing through the pivot points, and pivotallymounted means adapted to engage said pawl and biased toward said pawl bysaid spring for preventing said wheel from being rotated more than theamplitude of the reciprocatory movement of said pawl upon eachoscillation of said arm.

2. In a drive mechanism for a controller or the like, the combinationincluding a ratchet wheel, an oscillatable arm, a pawl pivotally mountedat the free end of said arm and adapted to engage said wheel, a cam foroscillating said arm whereby reciprocating movement is imparted to saidpawl, the amplitude of said oscillations being such that the wheel isnormally moved a unit distance upon each oscillation, a dog pivotallymounted upon a fixed support, a tension spring connected to said pawland dog at points farther from the axis of rotation of said wheel than aline passing through the pivot points of said pawl and dog, said springbeing adapted to maintain said pawl and dog in engagement with theratchet wheel and said arm in engagement with the cam oscillating it,and pivotally mounted means having a portion between the spring andratchet wheel adapted to engage said pawl and biased toward said pawl bysaid spring for preventing overrunning of said wheel.

3. In a drive mechanism for a controller or the like, the combinationincluding a ratchet wheel, an oscillatable arm, a pawl pivotally mountedat the free end of said arm and adapted to engage said wheel, a cam foroscillating said arm whereby reciprocating movement is imparted to saidpawl, the amplitude of said oscillations being such that the ratchetwheel is normally moved a unit distance upon each oscillation, a dogpivotally mounted upon a fixed support, a tension spring connected tosaid pawl and dog at points farther from the axis of rotation of saidwheel than a line passing through the pivot points of said pawl and dog,said spring being adapted to maintain said pawl and dog in engagementwith said ratchet wheel and said arm in engagement with the camoscillating it, pivotally mounted means having a portion between thespring and ratchet wheel and adapted to engage said pawl and biasedtoward said pawl by said spring, and means limiting the movement of saidpivotally mounted means toward the wheel and thereby the position of thespring.

4. In a drive mechanism for a controller or the like, the combinationincluding a pawl, a spring biasing said pawl and a ratchet wheel drivenby said pawl, and means including a pivotally mounted stop arm, a pinextending into the plane of said pawl carried by said arm, and aprojection on said arm having a curved portion engaged by said springfor preventing said wheel from overrunning when actuated by said pawl.

5. In a drive mechanism for a controller or the like, the combinationincluding a pawl, a spring biasing said pawl and a ratchet wheel drivenby said pawl, and means including a pivotally mounted stop arm havingits end in theplane of movement of said pawl and a curved upper portionengaged by the underside of said spring for preventing said wheel fromoverrunning when actuated by said pawl.

6. In a drive mechanism for a controller or the like, the combinationincluding a support, a ratchet wheel mounted on said support, an armpivotally mounted on said support, a constant speed cam for oscillatingsaid arm, a pawl pivotally mounted at the free end of said arm andreciprocable thereby for rotating said wheel in a predetermineddirection, a dog pivotally mounted on said support for preventingreverse rotation of said wheel, all said pivot points being equidistantfrom each other and at a distance greater than the radius of the wheelfrom the axis of rotation of said wheel, a spring connecting said pawland dog and mounted thereon at points farther from the axis than a linepassing through the pivot points of said pawl and dog for maintainingsaid pawl and dog in engagement with the wheel and said arm inengagement with said cam, other means for rotating said shaft, a stoparm pivotally mounted on said support, having a portion lying betweenthe underside of said spring and the wheel adapted to be engaged by saidspring, a pin carried by said support limiting movement of said stop armtoward the wheel, the end of said stop arm extending toward the pawl andbeing provided with a portion lying in the plane of movement of saidpawl, said portion being so constructed and located with respect to thepawl that the pawl is wedged therebetween and the ratchet Wheel at theend of each reciprocation thereof by said arm for preventing overrunningof said wheel, said spring having a strength such that it permitsmovement of said stop arm and pawl when said shaft is rotated by saidother means.

'7. In a drive mechanism for a controller or the like, the combinationof a driven ratchet, a pawl engageable with the ratchet for periodicallymoving it, means for reciprocating said pawl through a predetermineddistance, said means including a spring for moving the pawl through itsdriving stroke, and a movably mounted stop arm urged in one direction bysaid spring and engageable with the pawl to prevent the pawl from movingthe ratchet more than the distance the pawl is moved.

8. In a drive mechanism for a controller or the like, the combination01' a driven ratchet, a pawl engageable with the ratchet for period-'ically moving it, means for reciprocating said pawl through apredetermined distance, said 9. In a drive mechanism ior'a controller orthe like, the combination of a driven ratchet, a pivotally mounted pawlengageable with the ratchet for driving it in one direction, a pivotallymounted dog engageable with the ratchet to prevent it from moving in theother direction, a pivotally mounted stop arm engageabie with the pawlto prevent the ratchet 'irom overrunning, and a spring engaging thepawl, the dog and the stop arm for biasing all of them in one. 10

direction.

7 CLIFFORD C. BRADBURY.

